[unreadable] Stem cells and the potential they hold for novel approaches to treating complex, debilitating diseases or conditions in humans have sparked unprecedented interest in research in this area. This attention is well deserved given the potential for novel cell-based therapeutic approaches to complex diseases and disabilities for which other approaches have, to date, failed to offer sufficient solutions. In addition, stem cells demonstrate a number of basic biological processes that are central to cellular function, including self-renewal and/or differentiation. These same processes underlie the development, differentiation and function of normal organs and tissues, and abnormalities in these processes are at the root of many severe diseases including cancer, neurodegenerative diseases, diseases affecting the heart and blood systems, and many other debilitating conditions. However, the ability to conduct experiments with human embryonic stem (ES) cells is currently limited by federal regulations, and even in the absence of such regulations, there remains a compelling need for research on the biology, function, and manipulability of ES cells in a relevant animal model prior to any attempt to apply stem cell-based therapeutic approaches to humans. In this application we propose to initiate experiments to develop the baboon as a new model system for studies of primate embryonic stem cells. Baboons offer a number of potential advantages as a model nonhuman primate system for studies of ES cell biology and applications that will be highly relevant to humans. Thus, in this R21 application, we propose three aims - 1) To derive at least 5 new ES cell lines from baboon embryos produced in vitro by assisted reproductive technologies, 2) To characterize each baboon ES cell line at the cellular level, including growth characteristics, karyotype, ability to self-renew, expression of markers characteristic of pluripotent cells, ability to undergo directed differentiation in culture, and ability to undergo spontaneous differentiation in vivo, and 3) To characterize each baboon ES cell line at the molecular level, including expression of genes associated with pluripotency in undifferentiated ES cells, suppression of pluripotency gene expression upon induction of directed differentiation in vitro, and both parent-of-originspecific monoallelic expression and allele-specific differential DNA methylation of two exemplary imprinted genes (H19 and Snrpn) in both undifferentiated and differentiated ES cells. [unreadable] [unreadable] [unreadable]